The invention relates to a heat exchanger comprising a multiplicity of pockets mutually stacked in a longitudinal direction and each defining two chambers juxtaposed in a lateral direction in such a way as to form part respectively of a first and a second row of chambers, as well as a U-shaped elementary path extending substantially in a plane perpendicular to the longitudinal direction from one to the other of said chambers in order to circulate a first fluid in thermal contact with a second fluid, two chambers of a same row, belonging to two neighboring pockets of the stack, being delimited in the longitudinal direction by respective walls placed one against the other, certain of these walls being provided with openings allowing a leaktight communication of fluid between the adjacent chambers, the exchanger additionally comprising an inlet pipe and an outlet pipe for the first fluid, disposed at a first longitudinal end of the exchanger, substantially in the alignment of said first and second rows respectively, and each communicating with one of the chambers.
Heat exchangers of this kind are especially used as evaporators in air-conditioning loops of vehicles, the first fluid being a coolant fluid circulating in the loop and the second fluid being air meant for the passenger compartment of the vehicle.
The object of the invention is to propose an arrangement of inlet and outlet pipes which allows a reduction in the space taken up by the heat exchanger, both when the first fluid circulates in four passes and when it circulates in six passes.
The invention especially relates to a heat exchanger of the type defined in the introduction and envisages that one at least of said pipes communicates with the corresponding chamber via an end box supplementing the stack of pockets at said first end.
Optional characteristics of the invention, complementary or substitutional, are set out below:
The end box defines two separate compartments situated respectively in the alignment of the two rows, each of said pipes communicating with the corresponding chamber via one of said compartments.
The compartment communicating with the inlet pipe is connected to the upstream end of an injection tube which traverses a part of the stack of pockets, in the longitudinal direction, so as to lead the first fluid to a first-row chamber remote from the first end.
Said U-shaped elementary paths define a circulation of the first fluid in six passes, the first and fifth passes starting from first-row chambers, the second and sixth passes ending at second-row chambers, the third pass starting from second-row chambers and the fourth pass ending at first-row chambers.
The end box defines a unitary interior space situated in part in the alignment of each of the two rows and communicating directly with the outlet pipe, the inlet pipe being connected to an injection tube which traverses the end box and a part of the stack of pockets, in the longitudinal direction, so as to lead the first fluid to a first-row chamber remote from the first end.
Said interior space communicates with the adjacent first-row chamber by an annular passage surrounding the injection tube.
Said U-shaped elementary paths define a circulation of the first fluid in four passes, the first pass starting from first-row chambers, the second pass ending at second-row chambers, the third pass starting from second-row chambers and the fourth pass ending at first-row chambers.
The inlet and outlet pipes are mutually staggered in height, the end box extending over a height greater than the chambers, partially opposite said U-shaped elementary paths.
The end box is formed by a flat and vertical end plate and by a dished plate joined, at its periphery and, if necessary, in a median zone separating the two compartments, in a leaktight manner to the inner face of the end plate.
The end plate, and optionally the dished plate, extend substantially over the full height of the exchanger.
The end plate and the dished plate are parts of a unitary plate mutually connected by a fold line.